It is possible that the Telerik.Web.UI.Skins
assembly is not updated, for example if it was locked by some process.
Please check the reference to this assembly in your project in order to verify that it points to a DLL file with the same version as the version of Telerik.Web.UI
) and that it points to a valid file at all.
You can also try restarting Visual Studio after the update and if the problem persists, remove the reference to Telerik.Web.UI.Skins
and manually create a new reference to the correct file and then restart Visual Studio again.
The following help article contains information about this error so I would suggest checking it as well: http://www.telerik.com/help/aspnet-ajax/introduction-troubleshooting-skins.html